1. Field of the Invention
The present invention relates to portable overlapping locking mats with uniformly sized plastic mats joined together to form structural support surface for use by persons or equipment. The edges of the mats have recessed upper and lower lips with finger projections extending from the upper lips that are sized to fit into openings of adjacent mats' lower lips securing the mats together. The mats can be placed into an overlapped and secured arrangement solely with machine equipment eliminating the need for manual handling of the mats.
2. Description of Related Art
Mats, utilized in a variety of embodiments, have long been used for the construction of temporary support surfaces. A few examples of patents that disclose various mat systems are as follows:    U.S. Pat. No. 6,214,428B1 (A laminated wooden support mat fitted with one or more wear mat or pad and are bolted together);    U.S. Pat. No. 4,289,420 (A wooden mat to form a roadway from interlocking mats, each mat being formed from a plurality of layers or boards, each layer being formed from boards parallel to each other and perpendicular to boards forming the adjacent layer, the layers being fastened together at points of intersection by screw shank nails or other fastening means.);
U.S. Pat. No. 4,875,800 (A temporary support structure with a plurality of panels. Each panel includes a first row of boards arranged in parallel side-by-side relationship, and a second row of boards arranged in parallel side-by-side relationship. The second row of boards is superimposed on the first row of boards and oriented perpendicularly thereto. A first plurality of panels defines a lower layer in which the second row of boards extends upwardly to define lower locking boards. A second plurality of panels defines an upper layer resting upon the lower layer wherein the second row of boards thereof extends downwardly to define upper locking boards intermeshed with the lower locking boards. Individual panels of the upper layer are intermeshed with a plurality of lower panels to create an interlocking relationship therewith.);    U.S. Pat. No. 4,973,193 (A matting system includes interlocking mats of four differing configurations. Each mat configuration consists of wooden boards fastened together to create from one to three layers of boards at various areas of the individual mats. When interlockingly installed a desired area is uniformly covered with three layers of boards. The upper, working layer of boards bears the vehicular traffic or equipment placement. The middle, intermediate layer of boards, consists of interlock boards which fittingly interlock with corresponding spaces of adjacent mats, and, interspaced boards to reinforce the weight bearing characteristics of the mats. The lower, contact layer of boards rest upon the terrain. Within a layer the boards are parallel to one another, whereas the boards of each layer are perpendicular to the boards of any adjacent layer. When installed each mat interlockingly overlaps or underlaps approximately one-third of the width and one-half of the length of laterally adjacent mats. Both lateral and longitudinal relative movement of any installed mat is substantially precluded by a portion of each mat unit being in frictional engagement with the terrain, by a portion of each mat unit overlapping interlocking with adjacent mats and all three layers of each mat laterally and longitudinally abutting other mats which are also in frictional engagement with the ground.);    U.S. Pat. No. 4,462,712 (A flooring system for use at a construction site such as an oil well drilling site. The flooring system is formed by interlocking a plurality of flooring units. Each of the flooring units includes a rectangular base section and a surface section attached to and overlaying the base section. One end of the rectangular base section is aligned with one end of the surface section which has at least one open-ended locking slot along its length. Located on the opposing end of the surface section is at least one locking tab formed from the surface section and projecting beyond and above the edge of the base section. The locking tab is aligned with the locking slot of the flooring unit).
Additionally, fastening devices are known to interconnect and secure flat shaped components such as mats. For example, U.S. Pat. No. 4,604,962 discloses an interlocking assembly for modular loading dock units, and U.S. Pat. No. 6,695,527 discloses a reusable overlapping mat system.
Any successful interlocking mat system used for support surfaces must provide substantial holding strength to prevent lateral and vertical separation of the mats. Some known mats utilize overlapping edges holding the mats by material interferences of the surfaces. The material interferences of the overlapping mats often do not fully secure the mats. Individual manual labor is typically necessary to install these mats. Other types of mats utilize separate locking devices that must be separately installed by individual after the interlocking mats are arranged in the preferred configuration.
In its preferred embodiment, the present mat does not utilize an external locking device and can be installed without individual manual handling of the mats. The mats are secured laterally and horizontally by insertion of the finger projection fitting into and underneath an adjacent mat and these mats can be installed without manual labor with just machine handling equipment. Alternatively, the mat can also utilize external locking pins or fastening devices.